I thought so (regarding expected outcome) although I don't remember when I noticed this behavior for the first time. The again maybe via Binary XML Securefile the balance could tip the other way (hopefully)

I am thinking that "ideally" Oracle maybe should maybe decide to do it all in memory anyway, for both mentioned situations, when it's concerning CLOBs and/or even maybe XMLType CLOBs (basicfile). There isn't that much performance gain to achieve, if there are no XMLIndexes in play.

Did you notice the "2 CBO cost difference" between the COLLECTION ITERATOR PICKLER FETCH loops. Interesting also to see that the initial XML/SEQUENCEFROMXMLTYPE and XQ/SEQUENCEFROMXMLTYPE are equal in cost. I wouldn't have expected that outcome beforehand.